Switch gear



A ril 16, 1929.

D. R. DAVIES SWITCH GEAR Filed Nov. 22, 1926 INVENTOR 04 via 1? 0a Wes.

i I I WITNESSES: @7436. 4%

Patented Apr. 16, 1929.

' UNITED STATES PATENT OFFICE.

-DAVID REGINALD DAVIES, OF DIDSBURY, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTBIG &, MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA.

- SWITCH GEAR.

Application filed November 22, 1926, Serial No. 149,931, and in Great Britain November 28, 1925.

My invention relates to electric switch apparatus and particularly to iron-clad switch gears.

.One object of my invention is to provide 4 5 an iron-clad switch gear that shall be operative by a horizontal movement of certain ,of the switching units.

Another object of my invention is to provide an iron-clad switch gear that shall be operated by a bodily movement of a circuit interrupter in a horizontal direction.

This invent-ion relates to electrical switch gear of the armoured or so-called iron-clad typeadapted to connect together two circuits, for instance a cable and busbars, by means of an oil circuit breaker, the various conductors and devices of the switch gear being enclosed in metal casings, some of which may be filled with solid insulating compound and others with oil. In 'such switch gear, it is a common practice to proyide isolating switches or contacts respectively between the terminals of the oil circuit breaker and the two circuits to be connected together, for instance, the conductors of an incoming cable and one'or more sets of busbars, the object being to permitthe oil circuit breaker to be completely isolated so that, it can be adjusted orrepaired and if necessary removed for this purpose, and the present invention particularly relates to this form of gear. It is also common practice to provide two sets of busbars to which the cable or other circuit can be alternatively connected and for this purpose, selector switches are provided between one terminal of the oil switch and the two sets of busbars, the present invention being notably applicable to such a feature.

A form of iron-clad switch gear is well known in which the terminals of the oil circuit breaker are connected to vertically or horizontally disposed plug contacts, which, together with the oil circuit breaker, form a vertically or horizontally movable portion of the switch gear which co-operates with a fixed portion comprising, for instance, a.

set of busbars, the end connections of a cable, appropriate conductors and a set of sockets connected with the busbars so that when the oil switch is moved with respect to this fixed portion of the switch gear it may be connected with, or isolated from, the busbars and the cable by the consequent engagement with, or disengagement from the plugs with the sockets.

According to the present invention, the movable portion of a switch gear comprises an oil circuit breaker the lateral part of which "contains conductors connected with the terminals of the oil circuit breaker and which extends horizontally with respect to a part of the fixed portion of the switch gear comprising devices such as busbars, cable terminals and appropriate conductors. Contact members connected with the conductors in said lateral part extend downwardly from the latter in pro is u: to co-operating contacts located in said fixed portion of the switch gear and connected with the devices therein, so that by horizontal movements of said movable portion of the switch gear, the circuit breaker may be connected with, or isolated from, the devices and also, if desired, selective connection may be made such as between a cable and alternative sets of busbars where these are provided.

lln carrying out the invention, the lateral part of the movable port-ion of the switch gear may be secured to the head of the oil circuit breaker and may be filled with solid insulating compound. The contact members, which may be of any suitable type, are connected with the circuit-breaker terminals 35 and may extend into the fixed portion of the switch gear through insulating bushings.

When duplicate busbars are provided, the contacts connected with the cable may be duplicated so that when the oil switch occupies either one of its extreme positions one terminal of the oil switch will be connected with the cable.

Complete isolation of the oil switch may be effected by moving it to an intermediate position wherein the downwardly projectingcontacts also occupy a position intermediate the pairs of contacts connected with the respective sets of busbars and the pairs of contacts connected with the cable. When A it is desired to remove the 'oil circuit breaker for repair or other reasons it may be lifted and carried away along with the lateral portion and the downwardly projecting con;- tacts. The chambers in which the isolating and or selector switches are located are preferably filled with .oil.

'In a convenient'arrangement the casings containing the two sets of contacts, namely, the busbar isolating or selector contacts and the cable isolating contacts, are located in front of one another in line with the oil circuit breaker above the busbar chamber or chambers and the cable entry box while the laterally extending portion containing the co-operating contacts connected with the terminals of the circuit breaker extends over and slides upon both of these casings when the movable portion of the switch gear is moved back and forth.

To enable the invention to be clearly understood it will now be described with reference to the accompanying drawings which illustrate, by way of example, two arrangements of iron-clad switch gear for carrying out the invention. Fig. 1 is a sectional elevational view of gear in which the isolating switch contacts are rigidly fixed to the portions of the switch gear. Fig. 2 is a similar View of a portion of a similar arrangement of switch gear in which isolating switch contacts are pivoted to the movable portion of the gear, and Fig. 3 is a sectional elevational view taken at right angles to that of Fig. 1 showing by way of example, a method of providing an earth or testing connection.

Referring to Figs. 1 and 2 of the drawings, the switch gear therein illustrated is for three-phase systems and comprises in general a main oil circuit breaker 1 comprising fixed contacts 2 and a movable bridge 3 located in an oil tank 4; two sets of busbars 5 and 6; the terminals 7 of a cable; isolating switches 8 and 9 in respective oil filled tanks 11 and 12; and conductors 13 and 14 between the terminals of the oil circuit breaker 1 and .the isolating switches 8 and 9.

The busbars 5 and 6 are disposed in compound filled armouring chambers 15; the cable entry box 16 is also filled with compound and contains a series transformer indicatedat 17; and the conductors 13 and 14 are located in a compound filled chamber 18. The illustrated switch gear also comprises switch operating and tripping mechanism 19, a withdrawable potential transformer 20 and a framework comprising pedestal portions 21 and 22.

In accordance with the invention, the metal casing 18 containing 'the conductors 13 and 14 is bolted or otherwise rigidly connected to the oil circuit breaker 1 and is arranged, together with the latter, to move in a horizontal direction with respect to the remainder of the switch gear comprising in general the busbars 5 and 6 and the cable entry box 16, isolation of the oil switch and also selection between the busbars 5 and 6 being obtained b moving the oil switch and casing 18 bac ards and forwards in a horizontal direction.

In greater detail, the isolating or selector.

switches 8 in Fig. 1 comprise two sets of fixed contact jaws 23 and 24 projecting upwardly through oil-tight insulating bushings from the busbars into the oil tank 11, and a set of cooperating contact blades 25 connected with the conductors 13 and projectin downwards through insulating bushings rom the casing 18 into the tank 11. The top of the oil tank 11 is provided with a slot or a set of slots 26 to permit the contacts 25 to be moved backwards and forwards to engage either of the contacts 23 and 24 or to assume an intermediate position of isolation. The isolating switch 9 similarly comprises two sets of upwardly extending fixed contact jaws 27 and 25 electrically connected together and to the cable terminals 7, and a set of contact blades 29 connected with the conductors 14 and projecting downwards from the casing 18 into the oil tank 12, the arrangement being such that when the contacts 25 of the selector switch 8 are connected with the busbars 5 or the busbars 6, the contacts 29 will be connected with the cable 7, the top of the oil tank 12 being likewise provided with a slot or slots 30 to permit the necessary horizontal movement. The head of the oil switch may be provided with rollers 31 (as indicated in dotted lines) adapted to run on rails or tracks 32 on the pedestal 22 for facilitating the movements of the movable part of the switchgear.

The necessary movements to be imparted to the oil switch, .for operating the isolating or selector switches may be effected by hand through rack and pinion or other gear (not shown), or by means of an electric motor (also not shown), the energization of which may be controlled from a switch-board or other remote point. Interlocks may be provided if desired for ensuring that the oil circuit breaker must be opened before the isolating and/or selector switches can be opened. Furthermore provision may be made, for earthing or testing'the cable or other conductors of the switch gear, when the oil switch is entirely removed or is moved to an isolated position.

In some cases the switch gear may be adapted to permit changing over from one set of busbars to the other without opening the circuit. To this end the contact in the selector switch tank carried by the movable portion of the switch gear may be made longer or broader, according to the type of switchcontacts employed, so that in the intermediate position of the movable portion said longer or broader contact is in engagement with the contacts of both sets of busbars. When this is done the sets of busbars will usually have been previously connected together elsewhere.

Referring to Fig. 2, the contacts 25 and 29 of the isolating switches 8 and 9, instead of being rigidly mounted with respect to the casing 18 and conductors l3 and 14, are pivoted at 33 and 34 respectively to the conductors which extend downwardly through the insulating bushings from the casing 18. The contacts and 29 as indicated by the dotted lines are caused to engage the contacts 23 or 24, 27 or 28, when the movable part is reciprocated, by reason of metal tipped insulating abutments mounted within the isolating switch tanks 11 and 12.

In either arrangement above described, when the movable portion of the switch gear occupies the illustrated intermediate position. the oil circuit breaker 1 is isolated from the busbars and from the cable. Although switches of the knife blade and jaw type are illustrated, it is to be understood that they may assume other forms such as plugand-socket or the brush type.

It will be noted that the construction also permits the oil circuit breaker along with the casing 18, conductors 13 and 14 and contacts 25 and 29 to be raised and entirely removed.

Referring to Fig. 3 in order that a member of the switch gear such as a terminal of the cable 7, may be earthed or connected to testing apparatus, a contact 36, shown only in Fig. 3, may be provided electrically connected with, and extending laterally from, the contacts 27 and 29 by means of a bracket 37. lhe contact 36 may conveniently be in the form of a socket. The upper portion of the switchgear, for instance the casing 18, is provided with a tubular aperture or spout 38 through which, when it is brought into a position wherein it is in alignment with-the socket 36, an insulated plug 39 connected with a testing or earthing cable 40 may be inserted. The aperture or spout 38 may be provided with a hinged lid 41.

It will be appreciated that various modifications in the construction and arrangement of the swtich gear may be made without departing from the scope of the invention. For instance, the invention is not'limit-ed to three phase gears nor to gears having duplicate sets of busbars. The earthing may be efi'ected in other ways such as by means of additional contacts which are engaged when .the movable portion of the gear is moved to tact terminals for the circuit breaker depending from the cover into the casing and alternatively engaging the first said contact terminals when the circuit breaker is moved bodily.

2. Circuit-breaker apparatus comprising a casing having its upper side open, a pair of separate contact terminals within the casing, a bodily movable circuit breaker mounted for horizontal movement and having a laterally extending cover for extending over and closing the opening in the said casing, the said cover comprising a housing for receiving insulating material, contact terminals for the circuit breaker extending through the under side of the cover into the casing for alternatively engaging the first said contact terminals, and conductors within the cover for connecting the second said contact terminals to the terminals bf the said circuit breaker.'

3. Circuit-breaker apparatus comprising a pair of enclosed separate bus bars, separate contact terminals connected thereto, a casing surrounding the contact terminals and having its upper side open, a bodily movable circuit breaker mounted for horizontal movement and having a laterally extending cover for extending over and closing the opening in the said casing, and contact terminals for the circuit breaker depending from the cover into the casing and alternatively engaging the first said contact terminals when the circuit breaker is moved bodily.

In testimony whereof, I have hereunto subscribed my name this second day of November, 1926. I

DAVID REGINALD DAVIES. 

